WO2011039991A1

WO2011039991A1 - Solar cell module

Info

Publication number: WO2011039991A1
Application number: PCT/JP2010/005807
Authority: WO
Inventors: Akio Higashi; Hiroshi Kubo
Original assignee: Fujifilm Corporation
Priority date: 2009-09-30
Filing date: 2010-09-28
Publication date: 2011-04-07
Also published as: TW201123493A; JP2011077252A

Abstract

A solar cell module includes a solar cell submodule having photoelectric conversion elements on an insulation layer formed on at least one side of a metal substrate and bonding/potting layers and protection layers laminated on top and bottom sides of the solar cell submodule. The solar cell module further includes a first lead wire connected to one electrode of a positive and a negative electrodes of the solar cell submodule, for pulling out the output of the one electrode, an electrical contact member for connecting the other electrode to the metal substrate, and a second lead wire connected to the metal substrate, for pulling out the output of the other electrode through the metal substrate and the contact member to the outside of the protection layers. The second lead wire is connected to the metal substrate at one or more positions thereof.

Description

SOLAR CELL MODULE

The present invention relates to a solar cell module comprising a laminate formed of a bonding and potting (filling) layer and a protection layer on both top and bottom surfaces of a solar cell submodule having a plurality of connected photoelectric conversion elements formed on an insulation layer and, more particularly, to a solar cell module achieving simplified wiring between the lead wires for collecting the output from the positive and the negative electrodes of the solar submodule on the outside and a connection box attached to the solar cell module to permit connection to the outside.

Today, intensive researches are being conducted in solar cells. Solar cell modules forming a solar battery each comprise on a substrate a solar cell submodule including a number of series-connected laminate-structured photoelectric conversion elements essentially composed of photoelectric conversion layers generating current by light absorption each sandwiched by a back electrode (lower electrode) and a transparent electrode (upper electrode).
Known solar cell modules include one formed by further providing such a solar cell submodule with a bonding and sealing (bond/seal) material and a protective material on both sides thereof, the top and the bottom sides, and integrally attaching a connection box on the bottom side for connection to the outside, subsequently providing an internal lead wire between the positive and the negative electrodes for collecting generated electricity formed separately on the respective sides of the solar cell submodule on the one hand and the connection conductor of the connection box.
To permit collection of the output from the positive and the negative electrodes, such a solar cell module is provided with metallic ribbons or the like soldered or otherwise attached to the terminal portions located at both ends of the solar cell submodule and routed back to be connected to the connection box with an insulation layer provided between them (see Patent Literature 1 and 2).

Patent Literature 1 describes a thin-film type solar cell module comprising thin-film type solar cells having formed on a transparent insulation plate electrically connected photovoltaic elements divided into a plurality of regions each composed of a transparent electrode layer, a thin-film type photovoltaic semiconductor layer, and a back electrode layer formed in this order and bus regions for collecting electricity at ends of the connected photovoltaic elements; a sealing means including a filling material and a bottom side protection cover for protecting the surface provided with the thin-film type solar cells; and a connection means for supplying electricity generated by the thin-film type solar cells to the outside; wherein the wiring from the bus regions to the connection means is embedded in the filling material, and wherein there is embedded in another filling material between the wiring and the back electrodes an unwoven glass fabric sheet or an unwoven synthetic fiber fabric sheet resistant to 160^oC heat.
The thin-film type solar cell module described in Patent Literature 1 has the filling material, the wiring, the unwoven glass fabric sheet or the unwoven synthetic fiber fabric sheet resistant to 160^oC heat, the bottom side protection cover that are secured, upon assembly thereof, by vacuum laminating technique.

According to Patent Literature 1, the bus regions are provided on both longer sides of a power generating region of the thin-film type solar cells. The bus regions each have formed therein solder-plated copper foils, which are connected in turn to the bus regions and to other solder-plated copper foils for outputting electricity to the outside (see Fig. 1). The other solder-plated copper foils are bent in a substantially L-shape so as to project from the power generating region of the thin-film type solar cells at a position close to the center of the shorter sides thereof. These other solder-plated copper foils are connected to the connection box (see [0033] and [0034]).

Patent Literature 2 describes a solar cell module comprising thin-film solar cells including photoelectric conversion elements formed on a film substrate, a bond/seal material and a protective material laminated on both top and bottom sides of the thin-film solar cells, a connection box for connection to the outside integrally attached on the bottom side, and internal lead wires insulated in a section thereof between a connection conductor of the connection box and the positive and the negative electrodes provided at both ends of the solar cells to permit collection of electricity, wherein each internal lead wire is connected at one end thereof to one of the electrodes of the solar cells and laid along the periphery of the solar cells in such a manner as to make a detour around the solar cells and wherein the internal lead wires are sandwiched together with the solar cells by the bond/seal materials to secure sealing (see Claim 1 and Fig. 1).
According to Patent Literature 2, the connection portion of one end of each lead wire is soldered to one of the electrodes of the solar cells or electrically connected thereto by a conductive adhesive tape. The other end of each lead wire is bent and erected in an L-shape toward the bottom side, then passed through the slits of the bond/seal material and the bottom side protective material so as to project from the bottom side of the module, and connected by soldering to the connection terminals of the connection box located in such a position of the module as to register with the position where the lead wires project from the bottom side (see Figs. 2 and 4 and paragraph [0017]).

[PATENT LITERATURE 1] JP 3121810 B
[PATENT LITERATURE 2] JP 2004-31646 A

TECHNICAL PROBLEMS

In the Patent Literature 1 has a problem that the other solder-plated copper foils, the internal wiring, which need to be routed from the solder-plated copper foils of the bus regions to a proximity of the center of a shorter side of the power generating region as described above, increase the cost of the wiring material.
Further, in the solar cell module described in the Patent Literature 1, since the filling materials, the wiring, the unwoven glass fabric sheet or the unwoven synthetic fiber fabric sheet resistant to 160^oC heat, and the bottom side protection cover are disposed, assembled and then secured by vacuum laminating technique, the surface of the solar cell module is liable to locally bend and deform and, as a result, swell along the wiring path along which the other solder-plated copper foils are provided.
Thus, the solar cell module described in Patent Literature 1 has a drawback that swells created along the other solder-plated copper foils cause damage or locally concentrated stress, resulting in decreased reliability of the solar cells.

The Patent Literature 2 has a problem that routing the lead wires and other wiring of the solar cell module requires long lead wires insulated from the electrodes of the solar cells to the connection box and hence increases the cost of the wiring materials.
Thus, the solar cell modules in both Patent Literature 1 and 2 require long wiring and therefore have complicated wiring layouts, which reduces work efficiency in wiring process in the module installation procedure. Further, the poor work efficiency in wiring process in the installation procedure may damage the solar cells and may thus develop product quality problems. As described above, Patent Literature 1 and 2 have drawbacks of developing problems related to product quality and reliability.

An object of the present invention is to overcome the above problems associated with the prior art and provide a solar cell module with a simplified wiring configuration.

SOLUTION TO PROBLEMS

To achieve the above objects, the present invention provides a solar cell module comprising a solar cell submodule having a metal substrate, an insulation layer formed on at least one side of the metal substrate, and photoelectric conversion elements formed on the insulation layer and connected to each other; two bonding and potting layers laminated on both top and bottom sides of the solar cell submodule, respectively; two protection layers, each laminated on an outside of each bonding and potting layer; a first lead wire connected to one electrode of a positive electrode and a negative electrode of the solar cell submodule, for pulling out an output of the one of the positive electrode and the negative electrode to an outside of the two protection layers, an electrical contact member for connecting the other electrode of the positive electrode and the negative electrode of the solar cell submodule to the metal substrate, and a second lead wire connected to the metal substrate, for pulling out an output of the other electrode through the metal substrate acting as a conductor and the electrical contact member to the outside of the two protection layers, wherein the second lead wire is connected to the metal substrate at one or more positions of the metal substrate, and electrically connected to the other electrode connected to the metal substrate through the electrical contact member.

Preferably, the solar cell submodule further comprises a first connection member provided on the one electrode, and the first lead wire is connected through the first connection member to the one electrode of the solar cell submodule.
The second lead wire is preferably connected to the metal substrate at a position close to the first connection member.
Preferably, the solar cell submodule further comprises a second connection member provided on the metal substrate, and the second lead wire is connected through the second connection member to the metal substrate.
The first lead wire and the second lead wire preferably have their respective tips connected to a connection box provided on the outside of the protection layer formed on the bottom side of the solar cell submodule.
Preferably, the first lead wire and the second lead wire have their respective tips projecting substantially vertically with respect to the protection layer on the bottom side of the solar cell submodule and connected to the connection box.

The second connection member is preferably a conductive member in the form of a strip provided on the metal plate or an external connection jig clamping the metal substrate.
Preferably, the second lead wire and the external connection jig are electrically connected by a screw, a crimp contact, or a solder.
Preferably, the external connection jig is provided at least in one position on the metal substrate.

Preferably, the metal substrate is formed of an aluminum plate, a stainless steel plate, or a steel plate, and the insulation layer is an oxide film, a nitride film, or an oxynitride film made of one of aluminum, silicon, titan, and iron.

The photoelectric conversion elements preferably comprise back electrodes, photoelectric conversion layers, and transparent electrodes.
The photoelectric conversion layers are preferably formed of a compound semiconductor having at least one kind of chalcopyrite structure.
The photoelectric conversion layers are preferably formed of at least one kind of compound semiconductor containing an Ib group element, a IIIb group element, and a VIb group element.
Preferably, the photoelectric conversion layers are formed of at least one kind of compound semiconductor composed of at least one kind of Ib group element selected from the group consisting of Cu and Ag, at least one kind of IIIb group element selected from the group consisting of Al, Ga, and In, and at least one kind of VIb group element selected from the group consisting of S, Se, and Te.

ADVATAGEOUS EFFECTS OF INVENTION

According to the solar cell module of the invention, the metal substrate itself can be adapted to conduct electricity and act as a conductor and, when collecting the output from the positive electrode or negative electrode, the lead wire from one of the positive electrode and the negative electrode need not be routed a long length so that wiring configuration can be simplified. Therefore, the length of the whole wiring in the solar cell module can be shortened. Hence, the material costs for wiring can be reduced. Further, solar cell module fabrication costs, installation costs, and the like can be reduced.

Further, the solar cell module of the invention permits improvements on the product quality and reliability of solar cell modules by virtue of a simplified wiring configuration. Further, since the connection box of the solar cell module may be located at an end in lieu of the center of the solar cell module, the aesthetic appearance can also be improved, increasing the product value of the solar cell module.
According to the solar cell module of the invention, a plurality of external connection jigs may be provided to facilitate wiring between solar cell modules and permit serial or parallel connection thereof as desired.

Fig. 1 is a schematic perspective view of the solar cell module according to a first embodiment of the invention. Fig. 2 is a schematic top plan view of a solar cell submodule used in the solar cell module according to the first embodiment of the invention. Fig. 3 is a schematic cross section of the solar cell module illustrated in Fig. 2. Fig. 4 is a schematic perspective view of a part of a wiring configuration in the solar cell submodule used in the solar cell module according to the first embodiment of the invention. Fig. 2 is a schematic perspective view of the solar cell module according to a second embodiment of the invention. Fig. 6 is a schematic top plan view illustrating a solar cell submodule used in the solar cell module according to the second embodiment of the invention. Fig. 7 is a schematic cross section of a part of a wiring configuration in the solar cell submodule used in the solar cell module according to the second embodiment of the invention. Fig. 8 is a schematic top plan view illustrating a solar cell submodule used in the solar cell module according to a third embodiment of the invention. Fig. 9A is a schematic perspective view of a first example of external connection jig for the solar cell submodule used in the solar cell module according to the third embodiment of the invention; Fig. 9B is a schematic perspective view of a second example of external connection jig for the solar cell submodule according to the third embodiment of the invention; Fig. 9C is a schematic perspective view of a third example of external connection jig for the solar cell submodule according to the third embodiment of the invention; and Fig. 9D is a schematic cross section of the third example of external connection jig illustrated in Fig. 9C as secured. Fig. 10A is a top plan view of the first example of external connection jig as connected to the solar cell submodule used in the solar cell module according to the third embodiment of the invention; Fig. 10B is a top plan view of the second example of external connection jig as connected to the solar cell submodule according to the third embodiment of the invention; and Fig. 10C is a top plan view of the third example of external connection jig as connected to the solar cell submodule according to the third embodiment of the invention.

DETAILED DESCRIPTION OF INVENTION

The solar cell module of the invention will be described below based on preferred embodiments illustrated in the attached drawings.
Fig. 1 is a schematic perspective view of the solar cell module according to a first embodiment of the invention. Fig. 2 is a schematic top plan view of the solar cell submodule used in the solar cell module according to the first embodiment of the invention. Fig. 3 is a schematic cross section of the solar cell module illustrated in Fig. 2.

As illustrated in Fig. 1, a solar cell module 10 according to the first embodiment of the invention comprises a solar cell submodule 12, a bonding and filling (potting) layer 14, a water vapor barrier layer (which corresponds to a protection layer of the invention) 16, and a top surface protection layer (which corresponds to a protection layer of the invention) 18 provided on the top side of the solar cell submodule 12, a bonding/filling layer 20 and a back sheet (which corresponds to a protection layer of the invention) 22 provided on the bottom side of the solar cell submodule 12, and a connection box 24 connected to a first lead wire 56 and a second lead wire 60 projecting from the back sheet 22 as described later.

The solar cell submodule 12, the bonding/filling layer 14, the water vapor barrier layer 16, and the top surface protection layer 18 provided on the top side of the solar cell submodule 12, and the bonding/filling layer 20 and the back sheet 22 provided on the bottom side of the solar cell submodule 12 are integrated by vacuum laminating treatment according to vacuum laminating technique.
The top side of the solar cell submodule 12 denotes the side for receiving light for obtaining electricity; the bottom side denotes the opposite side from the top side.

The connection box 24 is provided to collect electricity obtained by a solar cell module 10 on the outside and connected to an electricity supply cable or the like. The connection box 24 is secured by bonding and sealing to a proximity of a corner of a surface 22a of the back sheet 22 by, for example, a silicone resin.

The bonding/filling layer 14 is provided to seal and protect the solar cell submodule 12 and bond it to the water vapor barrier layer 16.
The bonding/filling layer 14 is formed, for example, of EVA (ethylene vinyl acetate) or PVB (polyvinylbutyral).

The water vapor barrier layer 16 is provided to protect the solar cell submodule 12 from moisture. The water vapor barrier layer 16 is formed of a transparent film made of, for example, PET or PEN, having an inorganic layer of, for example, SiO₂ or SiN formed thereon, or is formed of an inorganic layer made of, for example, SiO₂ or SiN sandwiched by transparent films made of, for example, PET or PEN.
The water vapor barrier layer 16 is not specifically limited in composition, provided that it meets given performance requirements such as moisture vapor transmission rate, oxygen transmission rate, etc.

The top surface protection layer 18 is provided to protect the solar cell submodule 12 from stain or smear and minimize the decrease of incoming light into the solar cell submodule 12 due to smear or stain. The top surface protection layer 18 is formed, for example, of a fluorinated resin film. The fluorinated resin used is, for example, EFTE (ethylene/tetrafluoroethylene copolymer). The top surface protection layer 18 has a thickness of say 20 micrometers to 200 micrometers.

The bonding/filling layer 20 provided on the bottom side of the solar cell submodule 12 has the same composition as the bonding/filling layer 14 provided on the top side and will not be described in detail.
The back sheet 22 is provided to protect the solar cell module 10 from under the bottom side thereof and secure insulation of the solar cell module 10. The back sheet 22 has a structure such that an aluminum foil is sandwiched by resin films of PET, PEN, or the like. The back sheet 22 is not specifically limited in composition.

As illustrated in Figs. 2 and 3, the solar cell submodule 12 according to this embodiment comprises, for example, a substantially rectangular metal substrate 30, an insulation layer 32 formed on a top surface 30a of the metal substrate 30, and an insulation layer 34 formed over the whole bottom surface 30b of the metal substrate 30. There is formed on a surface 32a of the insulation layer 32 a solar cell unit 36.

The solar cell submodule 12 illustrated in Fig. 2 is an integrated type and comprises back electrodes 38, photoelectric conversion layers 40, buffer layers 42, and transparent electrodes 44 superposed in this order on the surface 32a of the insulation layer 32; the back electrodes 38, the photoelectric conversion layers 40, the buffer layers 42, and the transparent electrodes 44 constitute the photoelectric conversion elements 50.

The back electrodes 38 are formed on the surface 32a of the insulation layer 32 so as to share a separation groove (P1) 39 with adjacent back electrodes 38. The photoelectric conversion layers 40 are formed on the back electrodes 38 so as to fill the separation grooves (P1) 39. The buffer layers 42 are formed on the surfaces of the photoelectric conversion layers 40. The photoelectric conversion layers 40 and the buffer layers 42 are separated from an adjacent photoelectric conversion layer 40 and an adjacent buffer layer 42 by grooves (P2) 43 reaching the back electrodes 38. The grooves (P2) 43 are formed in different positions from those of the separation grooves (P1) 39 separating the back electrodes 38.
The transparent electrodes 44 are formed on the surfaces of the buffer layers 42 so as to fill the grooves (P2) 43.
Opening grooves (P3) 45 are formed so as to reach the back electrodes 38 through the transparent electrodes 44, the buffer layers 42, and the photoelectric conversion layers 40. The photoelectric conversion elements 50 are connected in series to each other through the back electrodes 38 and the transparent electrodes 44. The photoelectric conversion elements 50 constitute the solar cell unit 36.

The photoelectric conversion elements 50 of this embodiment have an integrated type CIGS configuration such that, for example, the back electrodes 38 are molybdenum electrodes, the photoelectric conversion layers 40 are formed of CIGS, the buffer layers 42 are formed of CdS, and the transparent electrodes 44 are formed of ZnO.
Light entering the photoelectric conversion elements 50 from the side bearing the transparent electrodes 44 passes through the transparent electrodes 44 and the buffer layers 42 and causes the photoelectric conversion layers 40 to generate electromotive force, thus producing a current flowing, for example, from the transparent electrodes 44 to the back electrodes 38. Accordingly, the leftmost back electrode 38a in Fig. 3 has the positive polarity (plus polarity) and the rightmost back electrode 38b has the negative polarity (minus polarity).

The solar cell unit 36 of this embodiment may be fabricated by any of known methods used to fabricate CIGS solar cells. The separation grooves (P1) 39 of the back electrodes 38, the grooves (P2) 43 reaching the back electrodes 38, and the opening grooves (P3) 45 reaching the back electrodes 38 are formed by laser scribing or mechanical scribing.

In the solar cell submodule 12, a first connection member 46 is provided on the leftmost back electrode 38a having the positive polarity of the solar cell unit 36 as illustrated in Fig. 3. The first connection member 46 is formed, for example, of a conductive member in the form of an elongated strip. Materials of the conductive member include, for example, a conductive tape and a tin-coated copper ribbon. The conductive member, when formed of a tin-coated copper ribbon, is secured by ultrasonic soldering using lead-free solder such as Cerasolzer. In this case, the conductive member may be secured by applying solder in a continuous line or by periodically disposing bumps of solder. Otherwise, a tin-coated copper ribbon may be connected to the leftmost back electrode 38 using conductive adhesive material, conductive tape, and the like.
When there is a photoelectric conversion element 50 formed on the positive polarity back electrode 38a on which the first connection member 46 is to be provided, the photoelectric conversion element 50 is removed by laser scribing or mechanical scribing to expose the back electrode 38a where the first connection member 46 is to be formed.

The top surface 30a of the metal substrate 30 has an exposed region 52 at the right end thereof, for example, where no insulation layer 32 is formed. The exposed region 52 can be secured by masking it when forming the insulation layer 32. The exposed region 52 may be secured otherwise by, for example, laser-scribing the insulation layer 32.

There is provided an electrical contact member 48 for establishing conduction between the rightmost back electrode 38b having the negative polarity and a part of the top surface 30a of the metal substrate 30 corresponding to the exposed region 52. The contact member 48 is a conductive member secured by soldering so as to bridge and connect the rightmost negative polarity back electrode 38b and the part of the top surface 30a of the metal substrate 30 where the exposed region 52 is located. This conductive member may be one similar to that used to form the first connection member 46. The contact member 48 may be a solder applied so as to bridge and electrically connect the rightmost back electrode 38b and the part of the top surface 30a of the metal substrate 30 corresponding to the exposed region 52.
When there is a photoelectric conversion element 50 formed on the negative polarity back electrode 38b on which the contact member 48 is to be provided, the photoelectric conversion element 50 is removed by laser scribing or mechanical scribing to expose the back electrode 38b where the contact member 48 is to be provided.

As illustrated in Fig. 2, there is secured between the periphery of the metal substrate 30 and the solar cell unit 36 an exposed region 52a without the insulation layer 32 of the metal substrate 30. The exposed region 52a may be formed similarly to the exposed region 52 described above.
The exposed region 52a has a second connection member 58. The second connection member 58 may have the same configuration as the first connection member 46. Therefore, a detailed description of the second connection member 58 will be omitted.

According to this embodiment, the first connection member 46 is connected to the first lead wire 56 as illustrated in Fig. 1. The first lead wire 56 is insulated by an insulation sleeve 57 except its connection portions.
The second connection member 58 is connected to the second lead wire 60. The second lead wire 60 is insulated by an insulation sleeve 61 except its connection portions.
According to this embodiment, the first lead wire 56 has a positive polarity, and the second lead wire 60 has a negative polarity.

The first lead wire 56 is connected to the positive electrode 38a to permit collection of the output (potential) of the positive electrode 38a on the outside of the back sheet 22.
The second lead wire 60 is connected via the second connection member 58 to the metal substrate 30 and electrically connected to the negative electrode 38b through the metal substrate 30 acting as conductor and the contact member 48. The second lead wire 60 permits collection of the output (potential) of the negative electrode 38b on the outside of the back sheet 22.

In Fig. 4, where the

insulation sleeves

57, 61 are omitted, the first lead wire 56 is bent substantially in the form of a square bracket and routed so as to contour a lateral face 30c of the substrate 30, the surface 22a of the back sheet 22 to reach the side opposite from the metal substrate 30, and the tip 56a is bent so as to be substantially normal to the surface 22a of the back sheet 22 so that it stands upright substantially in the form of L shape.
Similarly to the first lead wire 56, the second lead wire 60 is bent substantially in the form of a square bracket and mounted so as to contour a lateral face 30c of the substrate 30 and the surface 22a of the back sheet 22 to reach the side opposite from the metal substrate 30, where the tip 56a is bent so as to be normal to the surface 22a of the back sheet 22 and erected so as to stand upright substantially in the form of L shape.
As illustrated in Fig. 1, the first lead wire 56 and the second lead wire 60 project through the back sheet 22 to be connected to the respective terminals in the connection box 24 (not shown).

To collect electricity from the solar cell submodule 12 according to this embodiment, the configuration wherein the metal substrate 30 used as a conductor, the exposed region 52a is secured by removing a part of the insulation layer 32, and the second connection member 58 is provided to eliminates the need to route the second lead wire 60 having a negative polarity so as to make a detour around the solar cell unit 36, which shortens at least the length of the second lead wire 60 to be routed and simplifies the wiring configuration.
As a result, the whole length of the lines disposed in the solar cell module 10 can be shortened and hence wiring costs can be reduced. Further, solar cell module fabrication costs, installation costs, and the like can be reduced.

The serial resistance of the metal substrate 30 acting as a conductive path varies with the metal material used as shown in Table 1 below for a solar cell module measuring 120 cm in length and 60 cm in width. As shown in Table 1, the serial resistance poses no problem even with an SUS430 substrate that offers a relatively high specific resistance. The serial resistance between shorter sides is a serial resistance as measured in the module's longitudinal direction.

Further, this embodiment permits improvements on the product quality and reliability of a solar cell module 10 by virtue of its simplified wiring configuration. Further, since the connection box 24 of the solar cell module 10 may be located at a corner of the solar cell module 10 in lieu of the center thereof, the aesthetic appearance can also be improved, and the product value of the solar cell module 10 can be increased.

The second connection member 58 preferably has a minimum possible length, provided that the conduction with the rightmost back electrode 38b is established. Thus, the range of the insulation layer 32 to be removed can be reduced to facilitate the manufacturing process whereas the second connection member 58 also can be shortened to reduce material costs.

Further, since the first lead wire 56 having the positive polarity and the second lead wire 60 having the negative polarity, positioned close to each other, can be connected to the connection box 24 on the bottom side of the metal substrate 30 close to an end thereof, which permits reducing the length of the first lead wire 56 and the second lead wire 60 on the bottom surface 30b of the metal substrate 30. This makes it possible to provide the solar cell module 10 with a high product quality and a high reliability having a simple configuration free from protuberances that might otherwise be produced by the first lead wire 56 and the second lead wire 60.

The solar cell module 10 according to this embodiment may be fabricated, for example, as follows.
First, the solar cell submodule 12 is provided on its top side with the bonding/filling layer 14, the water vapor barrier layer 16, and the top surface protection layer 18.
In the solar cell submodule 12, the first lead wire 56 and the second lead wire 60 are bent, kept parallel to each other, routed onto the bottom surface30b of the metal substrate 30, and passed through the through-holes made in given positions of the bonding/filling layer 20 and the back sheet 22 disposed on the bottom side of the solar cell submodule 12 so that their

tips

56a and 60a project from the back sheet 22.
Then follows lamination process performed at 150^oC for 15 minutes to achieve integrated configuration by vacuum laminating technique. Next, the first lead wire 56 and the second lead wire 60 are bent so as to stand upright substantially in L-shape.
Subsequently, the terminals of the connection box 24 are connected to the

tips

56a and 60a of the first lead wire 56 and the second lead wire 60. Thereafter, the connection box 24 is bonded and sealed to a proximity of a corner of the surface 22a of the back sheet 22 by, for example, a silicone resin.

According to this embodiment, the metal substrate 30 is provided on its top surface 30a and bottom surface 30b with the insulation layers 32, 34. The insulation layers 32, 34 are typically oxide insulating films having fine pores produced therein by anodizing a metal substrate. These oxide insulating films have an enhanced insulation performance.
The metal substrate 30 may be formed of a material such that the metal oxide films formed on the top and bottom sides thereof are an insulator.

Specifically, the metal substrate 30 may be formed of aluminum, zirconium, titanium, magnesium, copper, niobium, or tantalum or an alloy of these metals. In view of the costs and the properties required of the solar cells, the metal substrate 30 is most preferably formed of aluminum.
The metal substrate 30 may be formed by cladding the surfaces of a steel plate such as a mild steel plate or a stainless steel plate with rolled sheets of metal or molten metal cited above as usable to form the metal substrate 30.
According to this embodiment, the metal substrate 30 is preferably flexible. Thus, the solar cell module, the solar cells, and the like obtained using such metal substrate 30 can be flexible.

Where an aluminum plate is used to form the substrate 30, the insulation layers 32, 34 can be formed by anodization followed by a specific pore sealing treatment. The process of manufacturing the insulation layers 32, 34 may include various steps in addition to the essential steps.
Where an aluminum plate is used to form the substrate 30, the insulation layers 32, 34 may for example be formed, according to this embodiment, through a process including a degreasing step of removing attached rolling oil, a desmutting step of dissolving smut on the surface of the aluminum plate, a surface roughening step of roughening the surface of the aluminum plate, an anodizing step of forming anodized films on the surfaces of the aluminum plate, and a pore sealing step of sealing the micropores of the anodized films, thereby producing a substrate of the solar cells.

Where an aluminum plate is used to form the substrate 30, aluminum material that may be used include an alloy of a Class 1000 pure aluminum as defined by Japan Industrial Standard (JIS), an Al-Mn alloy, an Al-Mg alloy, an Al-Mn-Mg alloy, an Al-Zr alloy, an Al-Si alloy, or an Al-Mg-Si alloy and another metallic element (see "Aluminum Handbook, 4th edition)" (published in 1990 by Japan Light Metal Association). The aluminum plate may contain a trace amount of a metallic element such as Fe, Si, Mn, Cu, Mg, Cr, Zn, Bi, Ni, and Ti.

The aluminum plate typically has a thickness of 0.1 mm to 10 mm. Where an aluminum plate is used, the thicknesses thereof decreases as it undergoes anodization, washing prior to anodization, and polishing. Therefore, the thickness thereof needs to allow for such reduction in thickness.

Anodization is achieved by immersing the aluminum plate as the positive electrode in an electrolytic solution together with the negative electrode and applying a voltage between the positive and negative electrodes. Where necessary, the anodization may include steps of subjecting the aluminum plate to washing and polishing/smoothing processes. The negative electrode is typically formed of carbon, aluminum, or the like. The electrolyte is not specifically limited; preferably used is one or more kinds of acids selected from sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, and amidosulfonic acid to prepare an acidic electrolytic solution. The anodizing conditions vary with the kinds of electrolytes used and are not specifically limited. By way of example, appropriate conditions are an electrolyte concentration of 1 % to 80 %, a liquid temperature of 5^oC to 70^oC, a current density of 0.005 A/cm² to 0.60 A/cm², a voltage of 1 V to 200 V, and an electrolysis time of 3 minutes to 500 minutes. The electrolytic solution preferably contains a sulfuric acid, phosphoric acid, or oxalic acid or mixture thereof. Electrolytes as described above are used preferably with an electrolyte concentration of 4 mass% to 30 mass%, a current density of 0.05 A/cm² to 0.30 A/cm², and a voltage of 30 V to 150 V.

In anodization of the aluminum plate, oxidation reaction takes place from the surfaces and substantially vertically to produce anodized films. Where any of the above electrolytic solution is used, the anodized films obtained will have a number of fine columns tightly arranged having a substantially hexagonal form as seen in planar view. The fine columns each have a pore at the core, the bottom being somewhat rounded. There is formed at the bottom of the fine columns a barrier layer with a thickness of 0.02 micrometers to 0.1 micrometers. In lieu of the acidic electrolytic solution, a neutral electrolytic solution such as one containing boric acid, etc. may be used for electrolytic treatment, whereby anodized films having a denser composition can be obtained in place of those where the porous fine columns are arranged. After producing the porous anodized films using an acidic electrolytic solution, pore filling technique may be used to perform additional electrolytic treatment in order to increase the thickness of the barrier layer.

The thicknesses of the insulation layers 32, 34 formed of aluminum oxide films are not specifically limited, provided that the insulation layers 32, 34 have insulation properties and a surface hardness sufficient to prevent damage that may be caused by a mechanical impact during handling. An excessive thickness thereof, however, may present problems from a viewpoint of flexibility. Therefore, the insulation layers 32, 34 formed of aluminum oxide films produced by anodization preferably have a thickness of 0.5 micrometers to 50 micrometers; the thickness can be controlled by electrolysis time as well as galvanostatic electrolysis and potentiostatic electrolysis.

The insulation layers 32, 34 are not limited to aluminum oxide layers produced by anodization. The insulation layers 32, 34 are exemplified by aluminum oxide films, silicon oxide films, and titanium oxide films. The insulation layers 32, 34 are further exemplified by aluminum nitride films, silicon nitride films, titanium nitride films, and iron nitride films. The insulation layers 32, 34 are further exemplified by aluminum nitrogen oxide films, silicon nitrogen oxide films, titanium nitrogen oxide films, and iron nitrogen oxide films.
The insulation layers 32, 34 may be formed, for example, by anodization, a CVD method, a PVD method, or a sol-gel method. The insulation layers 32, 34 have a thickness of 1 micrometer to 100 micrometers, preferably 10 micrometers to 50 micrometers.

The back electrodes 38 and the transparent electrodes 44 of the photoelectric conversion elements 50 are provided both to collect current generated by the photoelectric conversion layers 40. Both the back electrodes 38 and the transparent electrodes 44 are each made of a conductive material. The transparent electrodes 44, provided on the side from which light is admitted, need to be pervious to light.

The back electrodes 38 are formed, for example, of Mo, Cr or W, or a material composed of two or more of these. The back electrodes 38 may have a single-layer structure or a laminated structure such as a dual-layer structure.
The back electrodes 38 have a thickness of 100 nm or more, preferably 0.2 micrometers to 0.8 micrometers.
The back electrodes 38 may be formed by any of vapor-phase film deposition methods as appropriate such as electron-beam deposition and sputtering.

The transparent electrodes 44 are formed, for example, of ZnO added with Al, B, Ga, Sb, etc., ITO (indium tin oxide), SnO₂, or a material composed of two or more of these. The transparent electrodes 44 may have a single-layer structure or a laminated structure such as a dual-layer structure. The thickness of the transparent electrodes 44, not specifically limited, is preferably 0.3 micrometers to 1 micrometer.

The buffer layers 42 are provided to protect the photoelectric conversion layers 40 when forming the transparent electrodes 44 and admit the light entering the transparent electrodes 44 into the photoelectric conversion layers 40.
The buffer layers 42 are formed, for example, of CdS, ZnS, ZnO, ZnMgO, or ZnS (O, OH) or a material composed of two or more of these.
The buffer layers 42 preferably have a thickness of 0.03 micrometers to 0.1 micrometers. The buffer layers 42 are formed, for example, by CBD (chemical bath deposition) method.

The photoelectric conversion layers 40 absorb the incoming light admitted through the transparent electrodes 44 and the buffer layers 42 to generate current. According to this embodiment, the photoelectric conversion layers 40 are not specifically limited in composition; they may be formed, for example, of a compound semiconductor having at least one kind of chalcopyrite structure. The photoelectric conversion layers 40 may be formed of at least one kind of compound semiconductor composed of a Ib group element, a IIIb group element, and a VIb group element.

For a high optical absorptance and a high photoelectric conversion efficiency, the photoelectric conversion layers 40 are preferably formed of at least one kind of compound semiconductor composed of at least one kind of Ib group element selected from the group consisting of Cu and Ag, at least one kind of IIIb group element selected from the group consisting of Al, Ga, and In, and at least one kind of VIb group element selected from the group consisting of S, Se, and Te. The compound semiconductor is exemplified by CuAlS2, CuGaS2, CuInS2, CuAlSe2, CuGaSe2, CuInSe2(CIS), AgAlS2, AgGaS2, AgInS2, AgAlSe2, AgGaSe2, AgInSe2, AgAlTe2, AgGaTe2, AgInTe2, Cu(In1-xGax)Se2(CIGS), Cu(In1-xAlx)Se2, Cu(In1-xGax)(S, Se)2, Ag(In1-xGax)Se2, and Ag(In1-xGax)(S, Se)2.

The photoelectric conversion layers 40 preferably contain CuInSe₂(CIS) and/or Cu(In,Ga)Se₂(CIGS), which is obtained by dissolving Ga in the former. CIS and CIGS are semiconductors each having a chalcopyrite crystal structure and reportedly have a high optical absorptance and a high photoelectric conversion efficiency. Further, CIS and CIGS have an excellent durability such that they are less liable to decrease in efficiency through exposure to light or other causes.

The photoelectric conversion layers 40 contain impurities for obtaining a desired semiconductor conductivity type. Impurities may be added to the photoelectric conversion layers 40 by diffusion from adjacent layers and/or direct doping. The photoelectric conversion layers 40 permit presence therein of a component element of I-III-VI group semiconductor and/or a density distribution of impurities; the photoelectric conversion layers 26 may contain a plurality of layer regions formed of materials having different semiconductor properties such as n-type, p-type, and i-type.
For example, a CIGS semiconductor, when given a thickness-wise distribution of Ga amount in the photoelectric conversion layers 40, permits control of band gap width, carrier mobility, etc. and thus achieves a high photoelectric conversion efficiency.

The photoelectric conversion layers 40 may contain single or two or more kinds of semiconductors other than I-III-VI group semiconductors. Such semiconductors other than I-III-VI group semiconductors include a semiconductor formed of a IVb group element such as Si (IV group semiconductor), a semiconductor formed of a IIIb group element and a Vb group element (III-V group semiconductor) such as GaAs, and a semiconductor formed of a IIb group element and a VIb group element (II-VI group semiconductor) such as CdTe. The photoelectric conversion layers 40 may contain any other component than a semiconductor and impurities used to obtain a desired conductivity type, provided that no detrimental effects are thereby produced on the properties.
The photoelectric conversion layers 40 may contain a I-III-VI group semiconductor in any amount as deemed appropriate. The ratio of a I-III-VI group semiconductor contained in the photoelectric conversion layers 40 is preferably 75 mass% or more and, more preferably, 95 mass% or more and, most preferably, 99 mass% or more.

When the photoelectric conversion layers 40 of this embodiment are CIGS layers, the CIGS layers may be formed by such known deposition methods as 1) co-evaporation methods, 2) selenization method, 3) sputtering method, 4) hybrid sputtering method, and 5) mechanochemical processing method.

1) Known multi-source co-evacuation methods include:
three-stage method (J.R. Tuttle et al, Mat. Res. Soc. Symp. Proc., Vol. 426 (1966), p. 143, etc.) and a simultaneous evaporation method by EC group (L. Stolt et al.: Proc. 13th ECPVSEC (1995, Nice) 1451, etc.).
According to the first-mentioned three-phase method, firstly, In, Ga, and Se are simultaneously evaporated under high vacuum at a substrate temperature of 300^oC, which is then increased to 500^oC to 560^oC to simultaneously vapor-deposit Cu and Se, whereupon In, Ga, and Se are simultaneously evaporated. According to the latter method or the simultaneous evaporation method by EC group, Cu excess CIGS is vapor-deposited in an earlier stage of vapor deposition, and In excess CIGS is vapor-deposited in a later stage.

Following methods are among those where improvements have been made on the above methods to improve crystallinity of CIGS films.
a) Method using ionized Ga (H. Miyazaki et al, phys. stat. sol. (a), Vol. 203 (2006), p. 2603, etc.)
b) Method using radicalized Se (a pre-printed collection of speeches given at the 68th Academic Lecture by Japan Society of Applied Physics) (autumn of 2007, Hokkaido Kogyo Univ.), 7P-L-6, etc.)
c) Method using radicalized Se (a pre-printed collection of speeches given at the 54th Academic Lecture by Japan Society of Applied Physics) (spring of 2007, Aoyama Gakuin Univ.), 29P-ZW-14, etc.), and
d) Method using light excitation process (a pre-printed collection of speeches given at the 54th Academic Lecture by Japan Society of Applied Physics) (spring of 2007, Aoyama Gakuin Univ.), 29P-ZW-14, etc.).

2) The selenization method is also called two-stage method, whereby firstly a metal precursor formed of a laminated film such as a Cu layer/In layer, a (Cu-Ga) layer/In layer, or the like is formed by sputter deposition, vapor deposition, or electrodeposition, and the film thus formed is heated in selenium vapor or hydrogen selenide to a temperature of 450^oC to 550^oC to produce a selenide such as Cu(In_1-xGax)Se₂ by thermal diffusion reaction. This method is called vapor-phase selenization method. Another method available for the purpose is the solid-phase selenization method whereby solid-phase selenium is disposed on a metal precursor film to achieve selenization by solid-phase diffusion reaction using the solid-phase selenium as selenium source.

The selenization method may be implemented in several ways: selenium is previously mixed in a given ratio into the metal precursor film to avoid abrupt volume expansion that might take place in selenization process (T. Nakada et al, Solar Energy Materials and Solar Cells 35 (1994) 204-214, etc.); or selenium is sandwiched between thin metal films (e.g., as in Cu layer/In layer/Se layer ...... Cu layer/In layer/Se layer) to form a multiple-layer precursor film (T. Nakada et al, Proc. of 10th European Photovoltaic Solar Energy Conference (1991) 887 - 890, etc.).

Among the methods of forming a graded band gap CIGS film is one whereby firstly a Cu-Ga alloy film is disposed, and an In film is disposed thereon, subsequently achieving selenization by inclining the Ga density in the film thickness direction using natural thermal diffusion (K. Kushiya et al, Tech Digest 9th Photovoltaic Scienece and Engineering Conf. Miyazaki, 1996 (Intn. PVSEC-9, Tokyo, 1996) p. 149, etc.)

3) Known sputter deposition techniques include:
one using CuInSe₂ polycrystal as a target, one called two-source sputter deposition using H₂Se/Ar mixed gas as sputter gas (J. H. Ermer, et al, Proc. 18th IEEE Photovoltaic Specialists Conf. (1985) 1655 - 1658, etc.) and
one called three-source sputter deposition whereby a Cu target, an In target, and an Se or CuSe target are sputtered in Ar gas (T. Nakada, et al, Jpn. J. Appl. Phys. 32 (1993) L1169 - L1172, etc.).

4) Known hybrid sputter deposition methods include one whereby metals Cu and In are subjected to direct current sputtering, while only Se is vapor-deposited (T. Nakada, et al., Jpn. Appl. Phys. 34 (1995) 4715 - 4721, etc.).

5) The mechanochemical processing method is a method whereby a material selected according to the CIGS composition is placed in a planetary ball mill container and mixed by mechanical energy to obtain pulverized CIGS, which is then applied to a substrate by screen printing and annealed to obtain a CIGS film (T. Wada et al, Phys. stat. sol. (a), Vol. 203 (2006) p. 2593, etc.).

Other methods of forming a CIGS film include screen printing method, close-spaced sublimation method, MOCVD method, and spray method. For example, the screen printing method or the spray method may be used to form a fine-particle film containing a Ib group element, a IIIb group element, and a VI group element on a substrate and obtain a crystal having a desired composition by, for example, pyrolysis treatment (which may be a pyrolysis treatment carried out under a VIb group element atmosphere) (JP 9-74065 A, JP 9-74213 A, etc.).

Next, a second embodiment of the invention will be described.
Fig. 5 is a schematic perspective view of the solar cell module according to the second embodiment of the invention. Fig. 6 is a schematic top plan view of the solar cell submodule used in the solar cell module according to the second embodiment of the invention. Fig. 7 is a schematic cross section of a part of a wiring configuration in the solar cell submodule used in the solar cell module according to the second embodiment of the invention.
The same components of this embodiment as those of the solar cell module 10 according to the first embodiment illustrated in Figs. 1 to 4 are given like reference characters, and a detailed description thereof will be omitted.

Similar to the solar cell module 10 (see Fig. 1) according to the first embodiment, the solar cell module 10a according to this embodiment as illustrated in Fig. 5 has a solar cell submodule 12a the bonding/filling layer 14, the water vapor barrier layer 16, and the top surface protection layer 18 provided on the top side of the solar cell submodule 12a, and the bonding/filling layer 20 and the back sheet 22 provided on the bottom side of the solar cell submodule 12a integrated by vacuum laminating treatment according to a vacuum laminating technique. The tip 56a of the first lead wire 56 and the tip 60a of the second lead wire 60 projecting from the surface 22a of the back sheet 22 are connected to the respective terminals in the connection box 24 (not shown), which is bonded and sealed by, for example, silicone resin to the surface 22a of the back sheet 22.

As compared with the solar cell submodule 12 according to the first embodiment (see Fig. 2), the solar cell submodule 12a used in the solar cell module 10a as illustrated in Fig. 6 has the second connection member 58 provided in an exposed region 52b on the side opposite from the side on which the exposed region 52 is provided (see Fig. 2) according to the first embodiment in lieu of in the exposed region 52a of the surface 30a of the metal substrate 30 (see Fig. 2). That is to say, the second connection member 58 is provided in the exposed region 52b secured by removing the insulation layer 34 in the position on the bottom surface 30b opposite from the side on which the exposed region 52a is located according to the first embodiment, with the metal substrate 30 between them. Another difference is that the second connection member 58 is shorter. Except the above difference, the structure of the solar cell submodule 12a according to this embodiment is similar to that of the solar cell submodule 12 (see Fig. 2) according to the first embodiment and therefore will not be described in detail.

Also in this embodiment, the second connection member 58 is connected to the second lead wire 60 insulated by the insulation sleeve 61.
Similar to the solar cell module 12 according to the first embodiment, the solar cell submodule 12a according to this embodiment as illustrated in Fig. 7 has the first lead wire 56 bent and routed so as to contour the lateral face 30c of the substrate 30, the surface 22a of the back sheet 22 to reach the bottom side of the solar cell submodule opposite from the metal substrate 30, where the tip 56a is bent so as to be substantially normal to the surface 34a of the insulation layer 34.
The second lead wire 60, which is provided on the side closer to the bottom surface 30b of the metal substrate 30 as illustrated in Fig. 7, is passed through the bonding/filling layer 20 and the back sheet 22 and bent so as to be substantially normal to the surface 22a of the back sheet 22.

Although different from the first embodiment of the solar cell module 10 in the manner in which the second lead wire 60 is bent and the positions of the through-holes made in the bonding/filling layer 20 and the back sheet 22 provided on the bottom side, this embodiment can be fabricated similarly to the solar cell module 10 according to the first embodiment.
According to this embodiment, the metal substrate 30, the insulation layers 32, 34, and the photoelectric conversion elements 50 may be the same as those described in the first embodiment.

Further, this embodiment, only different from the first embodiment only in the position in which the second connection member 58 is bent and the manner in which the second lead wire 60 is bent, can produce the same effects as the first embodiment.
According to this embodiment, since the second connection member 58 is provided on the bottom surface 30b of the metal substrate 30, the second lead wire 60 in this embodiment can be made shorter than in the first embodiment. Thus, the material costs can be further reduced. Further, since the second lead wire 60 need only be bent upright in lieu of being routed around the lateral surface 30c of the metal substrate 30, the work efficiency in fabrication process can be further increased.

Next, a third embodiment of the invention will be described.
Fig. 8 is a schematic top plan view of a solar cell submodule used in the solar cell module according to the third embodiment of the invention.
Fig. 9A is a schematic perspective view of a first example of external connection jig for the solar cell submodule used in the solar cell module according to the third embodiment of the invention; Fig. 9B is a schematic perspective view of a second example of external connection jig for the solar cell submodule according to the third embodiment of the invention; Fig. 9C is a schematic perspective view of a third example of external connection jig for the solar cell submodule according to the third embodiment of the invention; and Fig. 9D is a schematic cross section of the third example as connected of external connection jig illustrated in Fig. 9C.
Fig. 10A is a top plan view of the first example of connection jig as connected to the solar cell submodule used in the solar cell module according to the third embodiment of the invention; Fig. 10B is a top plan view of the second example of external connection jig as connected to the solar cell submodule according to the third embodiment of the invention; and Fig. 10C is a top plan view of the third example of external connection jig as connected to the solar cell submodule according to the third embodiment of the invention.
The same components of this embodiment as those of the solar cell module 10 according to the first embodiment illustrated in Figs. 1 to 4 are given like reference characters, and a detailed description thereof will be omitted.

As illustrated in Fig. 8, a solar cell submodule 12b used in the solar cell module according to this embodiment is different from the solar cell submodule 12 according to the first embodiment (see Fig. 2) in that the former is not provided with the exposed region 52 without the insulation layer and the second connection member 58, and that an external connection jig 70 is provided on the metal substrate 30 close to the joint between the first lead wire 56 and the first connection member 46 in lieu of the second connection member 58. Otherwise, the solar cell submodule 12b share the same configuration with the solar cell submodule 12 according to the first embodiment (see Fig. 2) and, therefore, the shared configuration will not be described in detail.

The external connection jig 70 illustrated in Fig. 9A is conductive and has the shape of, for example, a rectangular solid with a recess 72 cut on one side so that it has a cross section substantially in the form of a square bracket.
The external connection jig 70 has on its upper surface 71 closer to the top side of the solar cell submodule 12b the tip of the second lead wire 60, which is insulated by the insulation sleeve 61, secured by, for example, a screw 76.
Opposite faces 74 in the recess 72 of the external connection jig 70 each have formed thereon, for example, continuous triangular projections.
The external connection jig 70 is secured to the metal substrate 30 by fitting the recess 72 onto an end of the metal substrate 30. In the process, the triangular projections formed on the face 74 destroy the insulation layers 32, 34 to establish conduction between the second lead wire 60 and the metal substrate 30.
The opposite faces 74 are not limited to the above configuration and may each have a roughened surface, provided that they can destroy the insulation layers 32, 34.

The external connection jig 70 is not limited to the configuration illustrated in Fig. 9A. In lieu of using the screw 76, the second lead wire 60 may be connected to a crimp contact 78, for example, which is secured to the upper surface 71 closer to the top side of the solar cell submodule 12b by a rivet 80 as illustrated in Fig. 9B.

Another alternative is to use an external connection jig 70b as illustrated in Fig. 9C of which the recess 72 has flat opposite faces 74a unlike their counterparts of the external connection jig 70 illustrated in Fig. 9A. The external connection jig 70b is connected to the metal substrate 30 via solder 82 as illustrated in Fig. 9D.
In this case, the insulation layers 32, 33 need to be previously removed from the part of the metal substrate 30 to be clamped by the recess 72 of the external connection jig 70b. Thus, the external connection jig 70b is fitted onto the metal substrate 30, and the solder 82 is applied to the boundaries between the metal substrate 30 and a bottom face 72a of the recess 72 and faces 73 of the external connection jig 70b located on the side thereof from which the recess is cut to secure the external connection jig 70b to the metal substrate 30.
The external connection jig 70b has on its upper surface 71 closer to the top side of the solar cell submodule 12b the tip of the second lead wire 60, which is insulated by the insulation sleeve 61, secured by the solder 84. Thus, conduction is established between the second lead wire 60 and the metal substrate 30.

Although with any of the external connection jigs 70, 70a, and 70b illustrated in Figs. 9A to 9C, the second lead wire 60 is connected to the solar cell submodule 12b on the top side thereof, the configuration is not limited this way; the second lead wire 60 may be connected to the solar submodule 12b on the bottom side thereof similarly to the second embodiment.

Although the external connection jig 70 is provided close to the joint between the first lead wire 56 and the first connection member 46, the configuration is not limited this way.
For example, the external connection jig 70 may be provided close to an end of the contact member 48 as illustrated in Fig. 10A, or may be provided at the center of a side on the periphery of the metal substrate 30 as illustrated in Fig. 10B.
Alternatively, two or more external connection jigs 70 may be provided as illustrated in Fig. 10C, for example, where the external connection jigs 70 are provided in three positions: close to the first connection member 46, at the center of a side on the periphery of the metal substrate 30, and close to an end of the contact member 48. In that case, each of the external connection jigs 70 in the three positions may be provided with the second lead wire 60. Alternatively, the external connection jigs 70 may be provided in two of the three positions. In that case, each of the external connection jigs 70 in the two positions may be provided with the second lead wire 60. Thus, providing a plurality of external connection jigs facilitate wiring between solar cell modules and permit serial or parallel connections thereof as desired.

Similar to the first embodiment, the solar cell submodule 12b according to this embodiment has both the first lead wire 56 and the second lead wire 60 routed onto the side opposite from the metal substrate 30, and the tip 56a of the first lead wire and the tip 60a of the second lead wire are bent so as to be substantially normal to the surface 34a of the insulation layer 34.
Similar to the first embodiment, the solar cell submodule 12b, the bonding/filling layer 14, the water vapor barrier layer 16, and the top surface protection layer 18 provided on the top side of the solar cell submodule 12b, and the bonding/filling layer 20 and the back sheet 22 provided on the bottom side of the solar cell submodule 12b are integrated by lamination according to vacuum laminating technique to produce a solar cell module.

This embodiment also may use the metal substrate 30, the insulation layers 32, 34, and the photoelectric conversion elements 50 that are the same as described for the first embodiment.
As described above, this embodiment can produce the same effects as the first embodiment and, moreover, produce the same effects as the second embodiment because the second lead wire 60 may be connected to the bottom side of the solar cell module 12b.
According to this embodiment, moreover, conduction through the second lead wire 60 can be established using the external connection jigs 70, 70a without the need to remove the insulation layers 32, 34. Thus, work efficiency can be further increased as compared with the first embodiment.
Further, since the second connection member 58 is unnecessary, the step of mounting the second connection member 58 can be saved.

Although the first lead wire 56 connected to the first connection member 46 has a positive polarity and the second lead wire 60 has a negative polarity according to any of the above embodiments, assignment of polarities is not limited this way; the polarities of the first lead wire 56 and the second lead wire 60 may be reversed, in which case also the same effects may be produced in all the above embodiments.
Further, although all the above embodiments are provided with the connection box 24, configuration involving the connection box 24 is not limited this way; the configuration may be such that the solar cell module is not provided with the connection box and that the first lead wire 56 and the second lead wire 60 are connected to a connection box provided in some other place than the solar cell module.

The present invention is basically as described above. While the solar cell module of the invention has been described above in detail, the present invention is by no means limited to the above embodiments, and various improvements or design modifications may be made without departing from the scope and spirit of the present invention.

LEGEND

10 solar cell module
12, 12a, 12b solar cell submodules
14 bonding/filling layer
16 water vapor barrier layer
18 top surface protection layer
20 bonding/filling layer
22 back sheet
24 connection box
30 metal substrate
32 insulation layer
34 insulation layer
36 solar cell unit
38 back electrodes
40 photoelectric conversion layers
42 buffer layers
44 transparent electrodes
46 first connection member
48 electrical contact member
50 photoelectric conversion elements
52, 52a regions
54, 82 solder
58 second connection member
70, 70a, 70b external connection jigs

Claims

A solar cell module comprising:
a solar cell submodule having a metal substrate, an insulation layer formed on at least one side of said metal substrate, and photoelectric conversion elements formed on said insulation layer and connected to each other;
two bonding and potting layers laminated on both top and bottom sides of said solar cell submodule, respectively;
two protection layers, each laminated on an outside of each bonding and potting layer;
a first lead wire connected to one electrode of a positive electrode and a negative electrode of said solar cell submodule, for pulling out an output of said one of said positive electrode and said negative electrode to an outside of said two protection layers,
an electrical contact member for connecting the other electrode of said positive electrode and said negative electrode of said solar cell submodule to said metal substrate, and
a second lead wire connected to said metal substrate, for pulling out an output of the other electrode through said metal substrate acting as a conductor and said electrical contact member to the outside of said two protection layers,
wherein said second lead wire is connected to said metal substrate at one or more positions of said metal substrate, and electrically connected to the other electrode connected to said metal substrate through said electrical contact member.
The solar cell module according to Claim 1,
wherein said solar cell submodule further comprises a first connection member provided on said one electrode,
wherein said first lead wire is connected through said first connection member to said one electrode of the solar cell submodule and
wherein said second lead wire is connected to said metal substrate at a position close to said first connection member.
The solar cell module according to Claim 1 or 2,
wherein said solar cell submodule further comprises a second connection member provided on said metal substrate,
wherein said second lead wire is connected through said second connection member to said metal substrate.
The solar cell module according to any one of Claims 1 to 3, wherein said first lead wire and said second lead wire have their respective tips connected to a connection box provided on the outside of said protection layer formed on the bottom side of said solar cell submodule.
The solar cell module according to Claim 4, wherein said first lead wire and said second lead wire have their respective tips projecting substantially vertically with respect to said protection layer on the bottom side of said solar cell submodule and connected to said connection box.
The solar cell module according to any one of Claims 1 to 5, wherein said second connection member is a conductive member in a form of strip provided on said metal plate or an external connection jig clamping said metal substrate.
The solar cell module according to Claim 6, wherein said second lead wire and said external connection jig are electrically connected by a screw, a crimp contact, or a solder.
The solar cell module according to Claim 6 or 7, wherein said external connection jig is provided at least in one position on said metal substrate.
The solar cell module according to any one of Claims 1 to 8,
wherein said metal substrate is formed of an aluminum plate, a stainless steel plate, or a steel plate, and
wherein said insulation layer is an oxide film, a nitride film, or an oxynitride film made of one of aluminum, silicon, titan, and iron.
The solar cell module according to any one of Claims 1 to 9, wherein said photoelectric conversion elements comprise back electrodes, photoelectric conversion layers, and transparent electrodes.
The solar cell module according to Claim 10, wherein said photoelectric conversion layers are formed of a compound semiconductor having at least one kind of chalcopyrite structure.
The solar cell module according to Claim 10, wherein said photoelectric conversion layers are formed of at least one kind of compound semiconductor containing an Ib group element, a IIIb group element, and a VIb group element.
The solar cell module according to Claim 12, wherein said photoelectric conversion layers are formed of at least one kind of compound semiconductor composed of at least one kind of Ib group element selected from the group consisting of Cu and Ag, at least one kind of IIIb group element selected from the group consisting of Al, Ga, and In, and at least one kind of VIb group element selected from the group consisting of S, Se, and Te.